1. Core Case Study: Water Conflicts in the Middle East - A Preview of the Future
Many countries in the Middle East, which has one of the world’s highest population growth rates, face water shortages.
Figure 14-1

2. Water Conflicts in the Middle East: A Preview of the Future
Most water in this dry region comes from the Nile, Jordan or Tigris rivers.
Countries are in disagreement as to who has water rights.
Currently, there are no cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.

3. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
keeps us alive
moderates climate
sculpts the land
removes and dilutes wastes and pollutants
moves continually through the hydrologic cycle.
Only about 0.02% of the earth’s water supply is available to us as liquid freshwater.

4. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Comparison of population sizes and shares of the world’s freshwater among the continents.
Figure 14-2

5. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
precipitation
infiltrates the ground and is stored in soil and rock (groundwater)
Evaporates
runs off (surface runoff) into bodies of water
The land from which the surface water drains into a body of water is called its watershed or drainage basin.

6. Unconfined Aquifer Recharge Area Evaporation and transpiration
Precipitation
Evaporation and transpiration
Evaporation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Figure 14.3
Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock where the water is confined under pressure. Some aquifers are replenished by precipitation; others are not.
Infiltration
Water table
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308

7. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
We currently use more than half of the world’s reliable runoff of surface water and could be using 70-90% by 2025.
About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources.
Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

8. Water in the United States
Average precipitation (top) in relation to water-deficit regions and their proximity to metropolitan areas (bottom).
Figure 14-4

9. Average annual precipitation (centimeters)
Less than 41
81–122
41–81
More than 122
Figure 14.4
Natural capital: average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). QUESTION: What is the water supply situation where you live or go to school? (Data from U.S. Water Resources Council and U.S. Geological Survey)
Fig. 14-4a, p. 309

10. Metropolitan regions with population greater than 1 million
Figure 14.4
Natural capital: average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). QUESTION: What is the water supply situation where you live or go to school? (Data from U.S. Water Resources Council and U.S. Geological Survey)
Acute shortage
Shortage
Adequate supply
Metropolitan regions with population greater than 1 million
Fig. 14-4b, p. 309

11. Case Study: Freshwater Resources in the United States
17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife.
Figure 14-5

12. TOO LITTLE FRESHWATER
About 41% of the world’s population lives in river basins that do not have enough freshwater.
Many parts of the world are experiencing:
Rivers running dry.
Lakes and seas shrinking.
Falling water tables from overpumped aquifers.

13. Stress on the World’s River Basins
Comparison of the amount of water available with the amount used by humans.
Figure 14-6

14. Case Study: Who Should Own and Manage Freshwater Resources
There is controversy over whether water supplies should be owned and managed by governments or by private corporations.
European-based water companies aim to control 70% of the U.S. water supply by buying up water companies and entering into agreements with cities to manage water supplies.

15. TOO LITTLE FRESHWATER
Cities are outbidding farmers for water supplies from rivers and aquifers.
Countries are importing grain as a way to reduce their water use.
More crops are being used to produce biofuels.
Our water options are:
Get more water from aquifers and rivers
desalinate ocean water
waste less water

16. WITHDRAWING GROUNDWATER TO INCREASE SUPPLIES
Most aquifers are renewable resources unless water is removed faster than it is replenished or if they are contaminated.
Groundwater depletion is a growing problem mostly from irrigation.
At least one-fourth of the farms in India are being irrigated from overpumped aquifers.

17. Withdrawing Groundwater
Trade-Offs
Withdrawing Groundwater
Advantages
Disadvantages
Useful for drinking and irrigation
Aquifer depletion from overpumping
Sinking of land (subsidence) from overpumping
Available year-round
Exists almost everywhere
Polluted aquifers for decades or centuries
Renewable if not overpumped or contaminated
Saltwater intrusion into drinking water supplies near coastal areas
Figure 14.7
Trade-offs: advantages and disadvantages of withdrawing groundwater. QUESTION: Which two advantages and which two disadvantages do you think are the most important?
No evaporation losses
Reduced water flows into surface waters
Increased cost and contamination from deeper wells
Cheaper to extract than most surface waters
Fig. 14-7, p. 313

18. Groundwater Depletion: A Growing Problem
Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S.
The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest).
Figure 14-8

19. Other Effects of Groundwater Overpumping
Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater.
Figure 14-11

20. Other Effects of Groundwater Overpumping
Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater.
Figure 14-10

21. Groundwater Pumping in Saudi Arabia (1986 – 2004)
Irrigation systems from the nonrenewable aquifer appear as green dots. Brown dots are wells that have gone dry.
Figure 14-9

22. Groundwater Depletion
Solutions
Groundwater Depletion
Prevention
Control
Waste less water
Raise price of water to discourage waste
Subsidize water conservation
Ban new wells in aquifers near surface waters
Tax water pumped from wells near surface waters
Buy and retire groundwater withdrawal rights in critical areas
Figure 14.12
Solutions: ways to prevent or slow groundwater depletion by using water more sustainably. QUESTION: Which two of these solutions do you think are the most important?
Set and enforce minimum stream flow levels
Do not grow water-intensive crops in dry areas
Fig , p. 316

23. USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER
Large dams and reservoirs
produce cheap electricity
reduce downstream flooding
provide year-round water for irrigating cropland
displace people
disrupt aquatic systems

24. Figure 14-13

25. Case Study: The Colorado Basin – an Overtapped Resource
The Colorado River has so many dams and withdrawals that it often does not reach the ocean.
14 major dams and reservoirs, and canals.
Water is mostly used in desert area of the U.S.
Provides electricity from hydroelectric plants for 30 million people (1/10th of the U.S. population).

26. The Colorado River Basin
The area drained by this basin is equal to more than one-twelfth of the land area of the lower 48 states.
Figure 14-14

27. Dam Removal
Some dams are being removed for ecological reasons and because they have outlived their usefulness.
In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S.
The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.
Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

28. TRANSFERRING WATER FROM ONE PLACE TO ANOTHER
Transferring water can:
make unproductive areas more productive
Promotes:
Investment
Jobs
Strong economy
cause environmental harm
encourages unsustainable use of water

29. Case Study: The Aral Sea Disaster
once the world’s 4th largest freshwater lake
Figure 14-17

30. Case Study: The Aral Sea Disaster
Diversion of water from the Aral Sea and its two feeder rivers
Used for irrigation
created a major ecological, economic, and health disaster
About 85% of the wetlands have been eliminated
roughly 50% of the local bird and mammal species have disappeared
the sea’s salinity has tripled
water has dropped by 22 meters
causing 20 of the 24 native fish species to go extinct

31. DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES
Removing salt from seawater by current methods is expensive and produces large amounts of salty wastewater that must be disposed of safely
Distillation:
heating saltwater until it evaporates, leaves behind waste in solid form.
Reverse osmosis:
uses high pressure to force saltwater through a membrane filter.

32. INCREASING WATER SUPPLIES BY WASTING LESS WATER
We waste about two-thirds of the water we use, but we could cut this waste to 15%
65-70% of the water people use throughout the world is lost through evaporation, leaks, and other losses
Water is underpriced through government subsidies
The lack of government subsidies for improving the efficiency of water use contributes to water waste

33. INCREASING WATER SUPPLIES BY WASTING LESS WATER
60% of the world’s irrigation water is currently wasted
improved irrigation techniques could cut this waste to 5-20%
Center-pivot, low pressure sprinklers sprays water directly onto crop
It allows 80% of water to reach crop
Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%.

34. (efficiency 60% and 80% with surge valves)
Drip irrigation
(efficiency 90–95%)
Gravity flow
(efficiency 60% and 80% with surge valves)
Figure 14.18
Major irrigation systems: because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new low-cost drip-irrigation systems may change this situation.
Center pivot
(efficiency 80%–95%)
Water usually pumped from underground and sprayed from mobile boom with sprinklers.
Above- or below-ground pipes or tubes deliver water to individual plant roots.
Water usually comes from an aqueduct system or a nearby river.
Fig , p. 325

35. TOO MUCH WATER
Human activities have contributed to flood deaths and damages.
Figure 14-23